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Water by Design

Water by Design

Children

Did you ever stop to think about water? That most precious of resources, is an amazing compound. Indeed, as we all know, without this commodity, there is no life.

No other substance appears as a solid, a liquid and a gas within earth’s normal temperature range. In fact within the normal temperatures found in most places on earth, we find water in the liquid form. No other common substance is liquid at ordinary temperatures.

This liquid phase of water is absolutely essential to all living cells and therefore, naturally, to all living creatures. Nutrients enter the cells in solution and all components of these living structures (cells) are associated with water.

Another remarkable characteristic of water is its heat capacity. This enables it to absorb a great deal of heat energy without itself warming much. This extra energy, which is absorbed without a resulting increase in temperature, is called latent heat. It takes, for example, five times the heat energy to raise water 1 degree Celsius as it does to raise air 1 degree Celsius. To raise 1 gram of water 1C takes 1 calorie. However to evaporate 1 g of water takes incredibly more energy. It takes 536 calories to convert 1 g of water to vapour at 100C. It also takes much energy to melt ice: 80 calories to melt 1 g of ice at 0C.

The heat capacity of water has a dramatic effect on the earth’s climate. It moderates temperature extremes, making the environment much more suitable for living creatures. Water not only absorbs vast quantities of incoming energy from the sun, but it also cools down much more slowly than most substances. Both the water free in nature and that in vegetation, exerts its effect on climate.

One of the most important reasons why plants cool a local climate is the large amount of evaporation from leaf surfaces. All plants, but particularly trees, can be considered as natural air conditioners. A single mature tree, for example, can evaporate as much as 400 L of water per day. The process of evaporating that much water uses up 230,000 kcal of energy. This means that a tree has an effect locally of five average room air conditioners (2500kcal/ hr) each running 20 hours per day. It is obvious that replacing vegetation in one’s yard with stones, will locally produce a heat island instead of cooling. Nevertheless some people do this in the name of protecting the environment!

Those of us who live in northern climates must also consider the properties of water as a solid. Most substances, as we all know, contract as they grow colder. Water, however, contracts only down to 4C. Below this point, however, water expands. Further marked expansion occurs when water freezes. Thus ice floats on the surface of liquid water. If water contracted upon freezing, as most substances do, then ice would sink. If this happened, then many places on earth would become a desert. The summer heat would soon prove inadequate to melt ice at the bottom of lakes and rivers. In time, all water would turn to solid ice except for a thin layer on the surface during the summer. The hydrologic cycle would have been drastically reduced long since. There would be little water vapour and no rain. Nothing could live save perhaps a few aquatic creatures.

We can indeed be thankful that our planet is so well endowed with water, a substance which, by virtue of its unusual properties, is absolutely essential to life. Obviously water was designed to support life. As in much else in nature, we see in the properties of this compound, abundant evidence of the Creator. It also doesn’t hurt to conserve this resource in so far as we are able!



October 2006

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